What is the purpose of using a tower climber's tether?

The purpose of using a tower climber's tether is primarily to secure the climber and prevent falls during ascent and descent. Safety is the foremost concern in tower climbing, and the tether functions as a critical safety device that connects the climber to the tower. This connection provides a reliable point of attachment that ensures, in the event of a slip or loss of grip, the climber is caught by the tether, greatly reducing the risk of falling. The design and implementation of tethers follow strict safety standards to protect technicians as they perform their work at significant heights.

The other options do not address the essential safety function of the tether. While enhancing climbing speed, holding tools, and measuring height can be aspects of a tower climber's work, they do not capture the primary purpose of the tether, which is to act as a life-saving device in cases of accidents.